Plant Physiol, October 2000, Vol. 124, pp. 899-910
Hydrogen Peroxide Yields during the Incompatible Interaction of
Tobacco Suspension Cells Inoculated with Phytophthora
nicotianae1
Amanda J.
Able,2
David I.
Guest, and
Mark W.
Sutherland*
Centre for Rural and Environmental Biotechnology and Department of
Biological and Physical Sciences, Faculty of Sciences, University of
Southern Queensland, Toowoomba, Queensland 4350, Australia (A.J.A.,
M.W.S.); and School of Botany, The University of Melbourne, Victoria
3010, Australia (D.I.G.)
Rates of H2O2 production by tobacco
suspension cells inoculated with zoospores from compatible or
incompatible races of the pathogen Phytophthora
nicotianae were followed by direct measurement of oxygen
evolution from culture supernatants following catalase addition.
Rates of HO2./O2
production were compared by following the formation of the formazan of
sodium,
3'-[1-[phenylamino-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate. In the incompatible interaction only,
both reactive oxygen species (ROS) were produced by the cultured host
cells in a minor burst between 0 and 2 h and then in a major burst
between 8 and 12 h after inoculation. Absolute levels of
H2O2 could not be accurately measured due to
its metabolism by host cells, but results are consistent with the
majority of H2O2 being formed via dismutation
of HO2./O2. The
effects of inhibitors of endogenous Cu/Zn superoxide dismutase (diethyldithiocarbamate) and catalase (3-amino-1,2,4-triazole and
salicylic acid) were also examined. Yields of ROS in the presence of
the inhibitors diphenylene iodonium, allopurinol, and salicylhydroxamic acid suggest that ROS were generated in incompatible host responses by
more than one mechanism.
1
This work was supported by the Australian
Research Council (grant no. A19601127) and by a University of Southern
Queensland PhD Scholarship (to A.J.A.).
2
Present address: Gatton Research Station, Queensland
Horticulture Institute, Queensland Department of Primary Industries, Locked Bag 7, MS 437, Gatton, QLD 4343, Australia.
*
Corresponding author; e-mail marksuth{at}usq.edu.au; fax
61-7-4631-2530.
© 2000 American Society of Plant Physiologists
